1. Technical Field
This invention pertains to the field of in-flight entertainment. Specifically, this invention pertains to methods and apparatus for communicating digital information between a system head-end, passenger interface electronics and personal electronic devices.
2. Description of the Prior Art
The term “in-flight entertainment system” typically refers to a collection of electronic equipment that collectively provide the facilities necessary to disseminate entertainment content or digital information to airline passengers. The in-flight entertainment, or “IFE” system deployed in a typical aircraft usually comprises some collection of equipment referred to as a “head-end”.
The head-end equipment may comprise an entertainment content server. In many cases, the entertainment content server may be a simple video-cassette-player (VCP). In other embodiments of an IFE system, the entertainment content server may be a sophisticated video-server that is configured to provide streaming video. Such content will normally be encoded into a digital form and stored on computer readable media comprising the video server. In either embodiment, the output emanating from the entertainment content server may be modulated onto a radio-frequency (RF) carrier. The RF carrier may then be disseminated throughout an aircraft using an RF distribution subsystem.
An RF distribution subsystem may comprise a wire-based cable plant capable of carrying RF energy and distributing the RF energy throughout the aircraft. Such cable types typically include coaxial cable that is capable of propagating RF signals without introducing significant degradation or excessive power loss. In some embodiments, the RF distribution system may comprise a hybrid configuration where RF signals are distributed through the aircraft using a combination of wire-based and fiber optic medium. In these embodiments, conversion units convert the RF signals from RF energy to modulated light as the medium changes. In yet other embodiments, the RF distribution system may be wireless altogether.
In most IFE systems, the physical cable comprises only a portion of the RF distribution subsystem. The RF distribution subsystem may further comprise components that are linked together by the physical cable. In one system, area distribution boxes, or “ADB”s, are used as part of a main trunk for the RF distribution subsystem. In one embodiment of a known IFE system, a first ADB receives an RF signal from a modulator that comprises the head-end equipment. After the first ADB receives the RF signal, it may propagate the RF signal through a segment of cable to another ADB. The second ADB may then propagate the RF signal to subsequent ADBs forming a distribution string.
Completing the RF distribution subsystem, each ADB may further comprise branching interfaces that propagate the RF signal to one or more seat boxes. Each of the seat boxes may serve one or more seats. Each seat box typically receives an RF signal from an ADB. The seat box may demodulate the RF signal in order to extract entertainment and/or data content carried by a modulated carrier. Each seat box may subsequently present the recovered entertainment or data content to a passenger seated in an airline seat. Seat boxes may also be chained sequentially to form branches off of the main distribution string formed by the ADBs.
IFE systems have recently been upgraded with the capability to provide on-demand video content and information content to airline passengers. To facilitate this type of on-demand service, the IFE systems typically comprise a control computer within the head-end electronics suite. A passenger local-area-network (LAN) may be deployed in parallel with the RF distribution subsystem. Many IFE systems closely associate the passenger LAN and the RF distribution system. In some embodiments, this is accomplished by using the ADBs that are primarily responsible for RF distribution, as network hubs.
In operation, the passenger LAN is used to communicate individual passenger requests for data or video content back to a control computer. The control computer may route these requests to either an entertainment content server or a data server installed in the head-end. Individual passengers may also use the passenger LAN quite directly. Typically, any passenger may connect a personal electronic device to a seat box. The seat box serves as an interface to the passenger LAN. Hence, the passenger LAN forms a classic intranet structure on board the aircraft and enables direct access to the on-board data server.
Each new IFE installation is usually tailored to a specific type of aircraft. For instance, the IFE system configuration for a Boeing 747 may differ significantly from the configuration used onboard an Airbus A330. Such differences are inevitable because of the inherent differences in each aircraft body type. Irrespective of the configuration any particular IFE system must adopt, several key design objectives remain constant.
One significant design objective is that of reducing the amount of weight the total IFE system contributes to the aircraft's take-off weight. The reason for this is that each pound of weight increases the overall fuel consumption for any passenger flight. Of course, this cost must either be passed on to the flying public or the airline operator must absorb it.
A significant weight reduction could be achieved if the passenger LAN could be combined with the RF distribution system. The reason for this is simple-wire is heavy. In known IFE systems, the passenger LAN requires installation of a separate physical medium. It would be highly advantageous if the passenger LAN's network data could be carried along the same physical medium as the entertainment content, i.e. the RF distribution subsystem.